If you’ve ever planted potatoes, you know the mystery of waiting. You can’t see what’s happening below the soil. So, what do potatoes look like when theyre growing? The process of underground tuber development is fascinating and understanding it makes you a better gardener.
This guide will show you exactly how potatoes form, what to look for at each stage, and how to know when they’re ready. You’ll learn to read the signs above ground that signal success below.
What Do Potatoes Look Like When Theyre Growing
Potatoes don’t grow like carrots or onions. They are tubers, which are swollen, underground stems. They form on special roots called stolons. The potato itself is a storage unit for the plant, packed with energy to survive and sprout again.
When they are developing, young potatoes look like small, pale bumps or nodules. They have a smooth, thin skin. As they mature, they swell into the familiar shapes we know. Their skin thickens and toughens, which is crucial for storage later on.
The Lifecycle of a Potato Plant
Knowing the stages helps you provide the right care at the right time. Each phase above ground matches a critical step in tuber development underground.
Stage 1: Sprouting and Planting
You start with seed potatoes. These are just small potatoes saved for planting. They have “eyes,” which are buds. After planting, the seed potato feeds the new plant until it can make its own roots.
Stage 2: Vegetative Growth
Green shoots push through the soil. The plant focuses on growing tall and leafy. This greenery is the engine, capturing sunlight to make energy. Underground, the root system and stolons begin to spread out horizontally from the main stem.
Stage 3: Tuber Initiation
This is the magic moment. It’s triggered by signals like day length and the plant’s maturity. The tips of the stolons stop growing longer. Instead, they start to swell. This is where the tiny, first potatoes begin.
- You’ll see the plant start to flower (in many varieties).
- This is a key sign that tuber formation has begun below.
Stage 4: Tuber Bulking
This is the main growth period. The plant sends all its energy from the leaves down to the tubers. They grow rapidly in size, gaining most of their weight now. Proper water and nutrients are essential during this phase.
Stage 5: Maturation
The plant’s job is done. The green tops (haulms) start to yellow, wilt, and die back. This is natural. Underground, the potato skins “set” and become firm. This hard skin protects the tuber, signaling it’s ready for harvest and can be stored for months.
What You’ll See at Harvest: A Visual Guide
When you carefully dig up a plant at different times, here’s the progression you’ll witness:
- Early Days (3-4 weeks after initiation): You’ll find tiny, marble-sized potatoes. Their skin is so thin you can rub it off with your thumb. They are often called “new” potatoes.
- Mid-Season (During bulking): Potatoes are now egg-sized or larger. Their shape is becoming defined—round, oblong, etc. The skin is still delicate but starting to toughen slightly.
- At Full Maturity: The potatoes are full-sized. Their skin is thick and doesn’t scrub off easily. For storage varieties, the skin is very tough. They detach easily from the stolons.
How to Check Progress Without Harming the Plant
You don’t have to dig up the whole plant to check. Practice “grabbling” or gentle hand-checking.
- Wait until the plant is well-established and has flowered.
- Choose a spot at the outer edge of the plant’s hill or mound.
- Gently move soil aside with your hands, going down 4-6 inches.
- Feel for tubers. If they’re too small, carefully cover them back up with soil. The plant will continue growing with minimal disturbance.
Common Issues in Tuber Development
Sometimes, things don’t go as planned. Here’s what might go wrong and how it affects the look of your potatoes.
Greening
If tubers are exposed to sunlight, they turn green. This is caused by solanine, a mildly toxic compound. It also makes the potato taste bitter. Always hill soil or mulch around plants to keep tubers completely covered.
Knobbiness or Misshapen Tubers
Inconsistent watering is the usual culprit. Periods of drought followed by heavy rain cause the tuber to stop and start growing unevenly, leading to strange, lumpy shapes. Aim for consistent, even soil moisture.
Small Tubers
A few things can cause this: overcrowded plants, not enough nutrients, or harvesting too early. Give each plant enough space and feed it properly during the bulking phase.
Cracks and Hollow Hearts
Rapid growth spurts, often from to much fertilizer or water, can cause internal cavities or external cracking. Again, consistency in care is the key to prevention.
Tips for a Perfect Potato Harvest
- Hill Your Plants: As plants grow, pile soil or straw around the base. This gives tubers room to form, prevents greening, and improves yield.
- Water Deeply and Evenly: 1-2 inches per week is ideal, especially from flowering through bulking. Drip irrigation is best.
- Know Your Variety: Early varieties mature faster and have thinner skins. Maincrop varieties take longer but develop thick skins for storage.
- Let Them Cure: After digging mature potatoes, let them dry on the soil surface for a few hours. Then cure them in a dark, humid place for 10-14 days to really toughen the skin for storage.
FAQ: Your Potato Questions Answered
Q: Can I eat potatoes right after I dig them up?
A: Yes! New, thin-skinned potatoes are a treat and don’t store well. For mature, storage potatoes, it’s better to cure them first.
Q: Why are my potato plants flowering? Does that mean potatoes are ready?
A: Flowering is a sign that tuber formation has started, but they are not ready yet. Harvest comes later, when the tops die back.
Q: How deep in the soil do potatoes actually grow?
A: Most tubers form in the top 6-10 inches of soil. That’s why hilling is so effective—it gives them more dark space to grow vertically.
Q: What does a potato plant look like when it’s ready to harvest?
A: The leaves and stems turn yellow and brown, and the plant looks dead. This is normal. For storage potatoes, wait 2-3 weeks after the tops have completely died back.
Q: Can you leave potatoes in the ground too long?
A: In cool, dry soil, they can be left for a while. But in wet or warm soil, they may start to rot or sprout. It’s best to harvest soon after maturity.
Growing potatoes is a rewarding lesson in patience and observation. By understanding what do potatoes look like when theyre growing underground, you can time your care and harvest perfectly. Pay attention to the signs, keep the soil mounded and even moist, and you’ll be rewarded with a homegrown crop that’s truly satisfying. There’s nothing quite like digging into the soil to find your own hidden treasure.